"Cycling" joke

It was the first day of the school year, and an elementary teacher was trying to get to know her students.

"What did you do this summer?" the teacher asked Suzie.

"Me and my family went to the beach a lot," Suzie answered.

"That sounds like fun," said the teacher. "How about you, Emma? What did you do this summer?"

"Me and my family rode our bikes together."

"That sounds lovely," said the teacher. She continued with all her pupils until she got to shy Mikey in the corner of the room.

"What did you do this summer, Mikey?"

"Nothing," the boy responded timidly.

"Did you do anything with your family?" the teacher asked, trying to draw Mikey out.

"Not really."

"Did you go to the beach?"

"No."

"Did you ride bikes?"

"No, never!" the boy burst out. "We can never ride bikes together!"

"Why not?" said the shocked teacher.

"I don't know," explained Mikey, "but dad always said, when mom and sis start' cycling together', it's time to get the hell out of town."